Method and apparatus for making dry carbon dioxide products



Aug. 23, 1932. c. L. JoNEs l 4 15873418 METHOD AND APPARATUS FOR MAKING DRY CARBON DIOXIDE PRDUGTS Filed Feb. 21,-1929 Patented Aug. 23, 1932 PATENTl OFFICE UNITED STATES CHARLES L. JONES, F PITTSBURGH,

PENNSYLVANIA,

AssreNon. 'ro nunon couronn- V TION 0F 0F NEW YORK, N. Y., A CORPORATION 0F DELAWARE METHOD AND APPARATUS IOR MAKING DRY CARBON DIOXIDE PRODUCTS appunti@ med rem-nary 21.1929. serial 110.341.680.

My present invention was made primarily as a solution of certain problems in the making of solid carbon dioxide from liquid by the well known snow making method, that is, by discharging of the liquid through a constrictled nozzle permitting release and sudden expansion of the liquid from its primary pressure and temperature of liquefaction. As is well known, the expansion results 1n freezing a part of the carbon dioxide to snowv while the remainder escapes as gas which may be returned and recompressed tional liquid or otherwise employed, as may be. desired.v

The liquid carbon dioxide has always contained appreciable percentages of water and as the snow nozzle and liquid discharged l therethrough quickly acqulre a temperature -loss of the product i commercial that was -in the liquid. If this is a substantial percentage of the block,'thevinsulating valueof the refrigerant gas that sublimates from the block, will be correspondingly less and the moisture is otherwise objectionable in certain uses to which the solid carbon dioxwhich heretofore has been an COmpI'GSSOIS removing substantially ide may be put.

'My invention has for its object asimple, cheap and remarkably all of the water and other liquid impurities from the liquid-carbon dioxide. Consequently, it may .be used for the production'of dry 'liquid carbon dioxide regardless of the purpose for which the liquid is used. It involves cooling the liquid, preferably by a partial release of pressurethereon, to freeze the water, and' novel means for collccting .'or so to speak precipitating, the Jfrozen crystals, segregated 4from the liquid. The partial expansion results incidentally in the production of dry carbon dioxide gas expensive product producible. only by special chemical driers. This product may be returned to the primary that make the liquid, it may be to make addi-' 110 or more below zero,.

effective method of percentage passed on to independent compressors ito make dry liquid for storage tank use, for any of the purposes in connection with which the dry liquid has commercial value, asl for instance, in mechanical refrigerating apparatus, wherein the refrigeration is by means of alternate compression and expansion of carbon dioxide.

While the normalireezing point of water is 32 F., I have discovdered that when the customary relatively small percentages of it are diffused throughout relatively large volumes of the liquid carbon dioxide, in an almost molecular state of subdivision, it can be sub-cooled far below the freezing pointv without crystallizing out unless suitable op-- portunity for agglomeration is aorded. have found dioxide from the compressors, usually at a temperature not much below critical temperature, usually as high as to 80 F., and at corresponding pressure, say 800'to 1200 pounds per anded for freezing outl of the water, a very considerable pressure drop is necessary to afford the required expansion and reduction of' temperature. Where the liquid is square inch, has to be exbeing expanded and cooled preparatory to use 1n snow making apparatus, a drop to 300 4pounds pressure affording a corresponding temperatage drop to approximatel7 for. my drying method an pansion and temperature drop may be emloyed, because for carbon dioxide snow makmg purposes, a very low temperature for the liquid delivered to the jet will result in a high yield of snow product. However, where the method is apphe'd merely to making of'dry liquid carbon dioxide -for other purposes, excessive pressure drop represents waste' and much higher temperatures will be found practicable. Where the liquid is to be used for mechanical re' frigeration. the should below enough to take out practically all of the water, as in the caseof snow making.

It' must be understood that while thepressure drop may vary considerably and the resultant liquid temperature may vary withzerorF. suitable evengreater'exfreezing out temperaturey inra; considerable range, the ressure lon the liquid at the low pressure siV e of the nozzle Ashould be high enough to prevent freezing of the carbon dioxide at this point and the incoming stream pf liquid CO2 must be warm enough to prevent the water from freezing within the nozzle. These conditions are usually easily attainable in an expansion nozzle such' as may be u used to pre-cool warm, 'freshly-compressed liquid C()2 by partial evaporation onits wasto a final snow making nozzle. v suggested above, sub-cooling of the water content, or even freezing out of the mii15' nutewater ice crystals must be accompanied by their collection to be effective, as other- `Wise such water will iiow with the liquid through relatively small passages to the snow making nozzle or deposit on and obstruct the .o -ilow passage walls. Such minutely diused ice ,particles or sub-cooled water will not readily agglomerate--or precipitate out of the liquid unless theyare brought into lintimate relation witheach other or to a' Acold surface to which they may clin In the resent case, I actually strain the iquid and mld up an agglomeration of iiufy water ice-snow inthe strainer, which may be penodically removed and emptied.

lo strainer, collector or precipitator is preferably arranged at the nozzle where the `coohng pressure dro'p occurs, preferably surround it but atsuiiicient distance to permit dissipation'of the violence of the jet yllibefore the screen is reached. It may even be arranged asa trap at a suitable point between the primary expansion nozzle andthe restricted passageways 'which the liquidl is, :subsequent y caused to traverse. c Theabove and other features of my invention will be more evident from the followg descri tion in connection with the accomawing,in which l'gure 1 is ammore' or less diagrammatic 45 Vview of theapparatus for producing and precipitating the water crystals from the liquid carbon' d loxide, interposed between the liq- A uid ma compressors fand the liquid usmg apparatus, as,ffor instance, a nozzle1 of lo the snow Y F 2 is a longitudinal sectionshowing a n Fig. 3 is a diagram of another modification.

For simplicity Vand convenience of illustral5 tion, Ithave not attempted Atoshow corrects or structural details -for the lvarious leoes 'of apparatusshown in tlie drawing.

ea roxlmate 'ressuresandtem ratures the f Y n pp Y p pe' The'v airly massive upper Vhead 19o of the above and hereinafter mentioned are suitable 00 vfor commercial snow making practice and of A course .subject to material 'variation'wlthin the spirit of the invention, as will be understood.. Y

. Fairlycool lowv pressure (10z contain- GI ing the -`usal amount" of ui impuritles.

' precipitator, here shown as a fine mesh basketV ,basket -m' place, butit will be obviousthat (principally water) enters the triple stave compressor-l0, l1, 12 through the pipe 13. It is forced in highly heated and compressed condition through pipe 14 tothe cooling coil 15 of the condenser 16 and from this coil the liquefied CO2 flows through a low resistance pipe 17 to theexpansion nozzle 18 which discharges into the evaporator 1 9. Theliqu id when it reaches the nozzle 'may be atwafpressure say of 1,000 pounds per square .inch and `at a temperature 'of around 80 F.- The evaporator isin the nature of an upright tank 'having a gas outlet pipe20 near its top Vanda liquid outlet pipe 2 1 in its bottom through which the liquid, substantially pre-cooled by the sudden release of pressure at nozzle 18 and partial evaporation in tank 19, flows `to second and third stage'evaporators (not shown) or direct to the liquid using apparatus, such for instance, as the expansion nozzle 22 of a snow chamber shownin dotted lines at 23.

A back pressure of say, 300 p oundsperl square inch is maintained inthe evaporator tank19 as by an adjustable valve 20c in the gas escape line 20 or by running-said line back to the inlet side 'of the third stage compressor, -or in any otherA manner. f AA control valve 20?) may also be'arranged in the liquid outlet line, In some cases it-may be desirable to segregate the dry gas leaving the evaporator from the wet'gas handled by the compressors, and it will be understood that many expedients may be resorted to for maintaining the de` sired pressure in the evaporator and forvhandling the gas escaping through pipe 20.

The primary expansion nozzle may be of the conventional snow making type, utoerating atl pressures too hi h for making C '2 snow and other details o the apparatus, as m thus far described, maybe conventional, the present invention being mpre particularly concerned with the extraction of the moisture from the warm and liquid` carbon dioxide supplied tothe evaporator, and the conseuent delivery of substantially dry liquid to t eliquid using apparatus and dry gasto" any desired point. c

With this in view, I'employ a strainer or nl 24 within which nozzle 18 dischar es and through which the expanded and coo ed CO,V must pa'on its way to the gas or liquid outlet as the case may be. The dral .shows one simple manner of removably this lll 'numerous othermeans may employed for evaporator tank 19 is-.prov'ided with an open- 1.25 ing 2 5 the upper portion of which is threaded to receive the lower threaded end of -a 'closure plug y This plug has a flange 26a seat-* ing gas-'tight :on Aa. boss 19d enclrcling the opening 19a." The lower or inner end of this 13 opening defines a support aunulus 27 carrying gasket 27a upon which an outwardly extendJ minal elbow section 31, the vertical portion of the latter being coupled in leak-proof manner to the vertical passageway 32 in the plug which communicates with the nozzle 18. The latter in this instance is carried bythe closure. plug and fitted into the enlarged lower end of bore 32. v Ihe` material of the basket must be such that a rather fine straining'eifect is obtained. 40 mesh wire gauze of Monel metal has proved suitable f in practice, but any foraminous, reticulated material might be used'f and a canvas'bag may be employed as a substitute or in addition -to the wire gauze andv may be either inside or outside the latter.

In operation, the warm liquid discharges with great violence in the nozzle 18, but it ex pands and partly gasifies to produce maximum cooling effect within a fraction of an inch -of the outlet and thenct refrigerant effect on the liquid produces a temperature drop to somewhat below the freezing point of water., say to around zero Fahrenheit. The violence of the. expansion is quickly dissipated in a region quite close to the nozzle mouth so that the inflowing and expanding gas does not strike the screen with sufficient force to -break up the ice crystals deposited in its interior and does not force themthrough the screen into the tank. Water, the principal liquid impurity, which hasbeen carried along by theCO2 stream in an almost molecular state of subdivision, crystallized out, the water ice crystals depositing on the inner surface of basket 2% in the form of a fine, fluffy snow containing, when the basketis full, some entrapped CO2 gas. L To remove-the basket and empty it, the coupling 30 is unscrewed and the closure plug 26 is unscrewedv and removed together with pipe line section 31 which it carries. The basket is then lifted out. Prior to these opy erations the pressure inthe evaporator has of course been reduced to substantially atmosf wisecontinuous processing of e CO2.

pheric.by a temporary cessatiohof the other- While I have shown a strain r for the purp0se,the invention in its broader aspect con- Gli' templates the provision of any collector surface over whichthe liquid is'caused to flow in intimate rela-tion so that the ice crystals will be coilected thereon.

Whether the liquid level in the evaporator tank is below the basket as shown or whether,

it rises to a level where the basket is partially this ange being firmly clamped 26a, 266. Preferably,

will immediately be f l heating coils 37a,

= In this case the essential eleing purposes.

similar to 'those of the ments are functionally system as the source of the modified expansion chamber adapted for expansion and cool-f' cooling, drying chamber 19 of Fig. 1, and accordingly similar reference characters with different exponents are used in Fig. 2. In this latter figure, the expansion chamber 19a, 196 is a horizontal tube andthe ends of. the

tube are equipped with symmetrically arv ranged expansion nozzles 18a, 186, fine mesh screens 24a, 246, and removable end closures there is only one high level gas outlet, 20a, and one low level liquid outlet, 216.v The screens being horizontal are preferably provided with lateral supporting legs or brackets 35, 85.

The device of Fi`g.,2 has better arange-4 ments for the removal of the snow collected in basket 24a and for gravity retention of water, either liquid or crystal, so that it does not naturally body ofliquid' CO2, particularly when the strainer is cleaned. The expansion chamber being horizontal, dams 36a, 366, which may be in the form of bunkers or indentations, are arranged between the freezing out region and the liquid and chamber. They are particularly necessary in the present ease by reason of the. further provision of means for meltingv the collected crystals in l off as liquid instead .of attempting to remove crystals from the basket. The means is diagrammatically indicated as being electrical 376. These heaters arel diagrarnmatically indicated as disposed within the basket,

surroundk the'same or might even be exterior Vto vthe, containerwalls 19a, 196.A -However,

but it is obvious that they might\ and necessarily fall into the gas discharge region of the ternatel'y and either lone ofthem may be dis- Either jet Ylas . maybe operatedelther simultaneously or al- I which maylead to traps not shown or may simply be blown throughcocks 39a, 39b.

The dry gas passing` oi' through 20a and the dry liquid fiowing down through 2lb may both be disposed of in any of the ways described in connection with conduits 20, 21 of Fig. 1.

While sizes are not the essence of the inven i pipes 20a, 2lb, may be 21/2 inch pipes of corresponding strength, preferably strip welded in the Walls of the expansion chamber.

The screen baskets may be approximately two feet,sixincheslongbysix inches diameter.

The dams 36a, 36?) may be 1/2 inch orso in Height. The expansion nozzles may be of the sizes and constructions commonly used for makingCO2 snow. v

However, conventional snow nozzles arev not necessary for inlet lof the liquid, and it is not necessary that the liquid be discharged in la jet within the basket. Furthermore, it is not necessary" t-o have the evaporating gas pass through the screen mesh of the basket and there are distinct advantages'in not hav- Ving it do so, because ifthe discharge is rapid or .of great velocity, it may tend to carry ice crystals through -the screen which would never be carried through by the slower percolation of lthe liquid.

Fig. 3 is a diagram showing an apparatushaving all -three of these modifications. In

.the apparatus actually used, there was an upright pipe 19x corresponding to the tank 19 ofwFig. 1, in which was suspended a basket 24:1: corresponding to 24; but oflarger dialn- `eter and in` proportion' tothe diameter ofthe tank. The latter is closed invat the bottom by a header which may be-bolted on and the top instead of, beingilat has, bolted on, 'an' upward extension 19a, and the warm liquid is' discharged. in this extension at a level considerably' above the top of the basket. The outlet pipe,20w, for escape of the cold gas, is located above the inlet for the liquid, the latter being thus a substantial distance above the basket and below the gas outlet. Thus, the gas jet velocities do' not interfere with the building up of the porous crystalline water deposits on the interiorl of the basket. It is to be noted vin this connection that even though the basket be of 40mesh wire and'surrounded by canvas,- the crystalline frost structure that is built up on the inside of the basket becomes in effect a filter or screen of far finer mesh than said screen or cloth.

ma diiiierent levels, as a convenient means for testing the level of the liquid carbon dioxide within the tank. If any of these cocks are ,below the level of the liquid opening, they Fig. 3 also shows that the tank 19 or 19a: A, be provided with a series of taps fv, at A Those impurities are very diiicult as well as expensive to get rid of by ordinary methods, but by my method, practically all of the [water and the less volatile 'andwater soluble 'impurities will be frozen out in the snowbasket and even if further purification is necessary, treatment of the dry, cold liquid with chemicals, charcoal, etc., will berelatively easy and inexpensive because of the relatively small amount of the remnant impurit and the cor-responding consumption of purlfying materials. v

What I claim is l. A method of removing water from liquid carbon dioxide which includes the steps of'suddenly partially relieving the pressure on the liquid carbon dioxide by dlscharge through a nozzle of snow-forming type to vaporize part of the carbon dioxide and bring the liquid to a pressure and correlative temperature much below freezing of water but above the triple point of the carbon dioxide and bringing the cooled liquid into intimate relation -with a suitable surface arranged to collect the water as frozen out crystals.

2. A method of removing water and the like from liquid .carbon dioxide which -includesy the steps of causing expansion and oxide, suflicient to. cool the liquid substantially below the freezing point of the water but limiting said cooling to a point substantially above the freezing point of the carbon dioxide liquid, and straining the minute crystalsI cf frozen out impurities fromthe cooled liqui A 1 i 3. A inethod of removing high freezing point fluid impurities from highly compressed liquid carbondi'oxide which includes 20 the steps of relieving: the pressure on the carbon dioxideand its entrained impurities to vaporizepart of the carbon dioxide to coolv it substantially'below the freezing point of. `the lmpurities but substantially above the freezing point of the carbon dioxide, and strainlng the minute crystals of frozen impurlties from the cooled carbon dioxide.

' 4. A method of removing high freezing point Huid impurities fromhighly compressed carbon dioxide which includes the steps of 25 ing carbon dioxide gas,

. enough to the resulting cold, water-free liquid.

coolingthe carbon dioxide with its entrained of the carbon dioxide, and bringing the cooled carbon dioxide into out impurities are collected.

5. A method of removing water from liquid carbon dioxide which includes the steps of suddenly partially relieving the pressure on the liquid carbon dioxide and cooling the liquid to the crystallizing temperature of the entrained water, and straining the cold liquid to remove the water in the form of ice crystals.

6. A method of producing dry liquid carbon dioxide which includes the steps of suddenly expanding the liquid to cool it toa temperature below the freezing point of water in order to crystallize the water content of the carbon dioxide'and straining the water ice crystals out of the cold liquid carbon dioxide.

7. A continuous process of producing dry liquid carbon dioxide for use in snow making which includes the steps of highly compresscondensing the compressed gas, partially expanding the condensate tolower its temperature below the freezing point of water whereby water impurities are precipitated out in the form of ice crystals and straining the coldl liquid to -remove the crystals' therefrom.

8. A method of simultaneously producing dry liquid carbon dioxide and dry carbon dioxide gas which includes the steps of expanding highly compressed liquid carbon dioxide through a nozzle into an evaporating chamber maintained at such pressure that Vthe carbon dioxide is 4partially gassied by the expansion and the temperature of the carbon dioxide is reduced to below the freezing point of water, screening both liquid and gaseous carbon dioxide to remove the water ice crystals which are formed and withdrawing the dry gaseous and liquid carbon dioxide products from the evaporator through separate outlets. Y

- 9. The method which "includes expanding compressed liquid carbon dioxide containing water through successive nozzles of the snowforming type, the steps including primary expansion to a pressure andtemperature low followed by screening outl ofthe water in crystal form, and the secondary; expansion being to pressures and temperatures suitable for production of solid carbon dioxide from 10.; Apparatus for drying carbonA dioxide including an expansion chamber having a liquid outlet at its lower end and a gas outlet v atits upper end, means to maintain the contents of the chamber under pressure, a nozzle for discharging liquid carbon dioxide into the chamber, means to supply liquid carbon diintimate proximity with a surface upon Awhich the crystals of frozen .low level liquid interposed between it cause solidifyingof the water but Anotlow enough to solidify the carbon dioxide oxide to the nozzle at a pressure considerably above the chamber pressure, and means providing a-fcollector surface upon which the ice crystals frozen out by the expansion and cooling of the carbon dioxide are adapted to precipitate.

11. Apparatus for drying carbon dioxide4 including an expansion chamber having a low level liquid outlet, and a high level gas outlet, means to maintain the contents of the chamber under pressure, a means fordischarging liquid carbon dioxide into the chamber, a

source of supplyl of liquid carbon dioxide to y the said discharge means at a pressure con# siderably above the chamber pressure, and means for collecting as ice crystals the water frozen out by the expansion and cooling of the carbon dioxide.

12. Apparatus including an expansion chamber having a outlet and a high level gas outlet, means to maintain the contents of the chamber under pressure, a nozzle for v discharging liquid carbon dioxide into the chamber, means to supply liquid carbon dioxide to the nozzle at a pressure considerably above the chamber pressure,

the expansion and cooling of the-carbon dioxide, said means comprising a fine mesh strainer spaced apart from `the nozzle and and said liquid outlet and through which theex from the nozzle necessarily ows.

13. Apparatus as in claim 12 and wherein the strainer is removable through a closure controlled opening in the chamber.

14. Apparatus as set forth in claim 12 and wherein the nozzle is carried by a closure and the latter upon removal provides clearance for the removal of the strainer.

15. Apparatus for .drying carbon dioxide including an expansion chamber having a low level liquid outlet and a high level gas outlet, throttle valves controlling the iiow from both outlets to maintain a pressure in the chamber, a nozzle for discharging liquid carbon dioxide into the chamber, means to p supply liquid carbonl dioxide to Vthe nozzle at a pressure considerably above the chamber pressure, and means for collecting as ice crystals the water frozen out by the expansion and cooling ofthe carbon dioxide preventing free How of gas or liquid to the outlets ex# cept in' streamsof very small cross-sectional area. y

-v 16. Apparatus -for drying carbonv dioxide including an expansion chamber having a low level, liquid outlet and a high level gas outlet, means to maintain the contents of the chamber under pressure, a nozzle for discharging liquid carbon dioxide into the chamber, means to supply liquid carbon dioxide tothe nozzle at a pressure considerably above the chamber pressure, and means for collectfor drying carbon dioxide l and means for collect- 4 ing as ice crystalsv the water frozen out by anding stream ing as ice crystals the water frozen out b -the expansion and cooling of the carbon d1- oxide, said collecting means being in the form of a fine mesh basket having walls sur-4 rounding but remote from the jet. .17. Apparatus for drying carbon dioxide including an expansion chamber having a low level liquid outlet and a high level gas outlet,'.means to maintain thfe contents of the y' 510 chamber under pressure, a nozzle for discharging liquid carbon dioxide into the chamber, means to supply liquid carbon dioxide l; to the nozzle at a pressure considerably above the chamber pressure, and means for collect- '15- ing as ice crystals the 4water frozen out b the expansion and cooling of the carbon d1- oxide, said collecting means bein in the form of a ne mesh basket having was surrounding but remote from the jetf'and elongated 2 in the direction of discharge of the jet from said nozzle so that all fluid liow therethrough I will be at relatively low velocity.A 18. Apparatus'as -in claim 17 in combination' with means for melting t e ice c s- '25 tals and separately collecting and draining oil the water without removing the basket.

-19. Apparatus as in claim 17 and wherein the expansion chamber is a lon horizontal# 1 ly disposed tubular element havlng opposite- I ..30 ly-directed, symmetrically di osed expan-v sion nozzles and collecting b site ends thereof.I

20. Apparatus as in claim' 17 and wherein Y f the expansion chamber-has a plurality of 35 transversely directed expansionnoz'zles and f collecting baskets each with' means for melt- ,.ing ice crystals and for separately collecting and draining oil' thewater. f 21. A method of purifying liquid carbon 4 dioxide having thereinimpuri'ties that freeze above the freezing point of liquidcarbon dioxide whichcomprises, reducing the pressure on the liquid so that-only a portion of it 'gasifes, tovpro -uce a temperature in the ets in- OPPQ- l 45 other portion of the liquid which i'slower than the solidifying point' of the impurities therein', limiting said reduction in pressure so that a temfperature aslow as vthe-solidify- 1 mg point o -the remainin liquid is no't 5 reached and then removing t e impurities.

' 22. A method of purifymg a body of liquid carbon dioxide whichcomprises, releas. ing pressure on the liquidjltlelproduce-,a temperature lower than the so fying int of.v

M the, impurities therein, limiting sal expaneP sion so that a tem rature lower than these.- .lidifying point o the liquid is notreached,

retainin the solidified impurities near the u point o expansion for subsequent removal o of said impurities and allowing the liquid Yto continue in its circulation.

Signed at: New York, in the county of New York and State of New York, this 16th day of February, A. D. 1929. 65 CHARLES L. JONES. 

